Firstly, the thing is that the amount of content and resources at lower mathematics level (college and before) is over saturated at this point. Even the most basic topics of Calculus have been done by 100s of people at very high levels of quality (For instance, see 3blue1brown , Professor Ghrist, Treffor Bazet on Youtube). It will most likely be that if you have a doubt at this level, it'd be cleared by watching these videos. Else, for those who wish to read there is a large number of online textbooks and notes.
Furthermore , there are many free auto solvers of basic exercises at highschool level. For instance, see Integral Calculator , Algebra simplifier etc.
The utility of MSE is that it gives support is that it is a resource for those higher topics and specific computations which are not frequently covered. If you're asking such things, then you should be mostly fine.
Personal advice:
I've gone through the questions on your account. They seem mostly okay. However, I'd advice you to improve your formatting and add your attempt. In about three questions I've seen you just say "from my work I got this equation", it would be more help for yourself and also apt for the site if you showed how you got it so other people can advice you on which step of your work has the error.
This particular question (and it's sequel) sort of frustrated me because it has a bit too much text. Try to write your problem straight to the point in the most concise way possible by usage of mathematical symbols. Seems you really only want the solution to the fourth image, not the third one.
Hope it helps you.